./' Indian Journal ofAnimal Seiences 69 (6):39g_99, June 1999

f'

Reproductive performance and disorders in mares

c N PLIROHIT', B S SII{RMA2 and KA cUpTA3

Rajasthan Agricultural Lrniversill., Bikaner, Rajasthan 334 001

Received: 5 May 199g; Accepted :3 Februarv 1999

ABSTRACT

Reproductive performance and disorders were.studied.ror thoroughbred mares &om r993 to 1996. The ol.erallmeanestruscyclelength@L)andestrusperiod(Ep)rvere 14.9g+1.12;d6.04+0.24gdays.BothELandEpdidnotvary between the years' buJ difreredsig*^nt-tiv u.l"een the months (p<0.0j). The overali mean coverings requiredper foal born were 9'87' Ivlaximum roatings o..urr.o in April 1rg) folr,oweJiy March (lg), February (1c),

^4ay (1 1)and June (4' e'6r% orthe roalings o..Gos.u;i;rt, to iio*reh i,"il.iii,Zr".*l11omins and only 6.r5% duringday hours. Mares evidenced foal heat with an ;r;;i of 7 .1.8t0 .7i duv*tl., flf irrg in 56.92%o cases. 1.l'e abortion percent was 13 '15' 40% of the tokl abortions being due to hvinniag. rn. ,.* rutio *u s 43.[7yomarebirths. Reproductive

flTf::il:* uncornmon' there were 4 '6t , 0 .;i ,;.;a a\d z .stfi, ii.r

"ipi...*"r rerention, vaginitis, pneumovagina

Key words : I\4ares, Reproductive performance

Mares are one of the least studred candidates in anima.lreproduction. With plenty of breed society impositions thereproductive perfbrmance in the thoroughlreOs is expectedto be low. Data of thoroughbred stud, Koiasar (Bikaner) wasanalysed fbr reproductive performance and disorders during1993-1996.

MATERIALS AND METHODSMares were detected in estrus using a teaser during the

breedrng season. Matings were given trom ttre third day ofestrus and then on alternate day till the end of estrus. Maresreturning to estrus were rebred till the end of the breedingseason. Strict daily records were kept and the esrus cycleiength (EL) was calculated as the period between disappear_ance ofone cycle and appearance ofsubsequent cycle. Closeobservations were done at the time of fujin; and the ibal_ing time recorded. Aborting ,ar.. rv... *t iitty monitoredarrd screened. Foaling mares were covered at the ibal heatexcept,.in abnormal fbalings. The breeding, lbaling and re_productive disorder data were analysed as fer Snedecor andCochran (1967).

RESULTS AND DISCUSSIONThe anaiysed data were grouped into breeding, tbaling

and reproductive disorder caGgory.Breeding: The overall mean+SE and the means for the

Present address : L2 Assistant pro fessor, C ollege o f Veterinaryand Animal Science, Bikaner.

3 Veterinary Officer, Veterinary Hospital, Tonk, Raiasthan.

years and months, lbr estrus cycle length (EL) and estrus

lT.od (EP) (Table l) revealed that theil, was sf,orter anOEP longer early in the breeding season whereas the Ep wassn11e1Tg EL longer tate in the UreeOing seuson. Both ELand.Ef drd not difler signiticantly betwe;rthe years understudy, however, the dift-erence beiween the months was sig_nificant (P<0.05) both fbr EL g1d Ep. Th; p..."r, tindingsare in agreemenr wirh those of Gintirer 1t e?+j wfro had re_ported wide difl'erences and cycle inegularities (including

Table 1. kast-square means and their SE for estrus cycle andestrus period (mean + SE)

Nfaineffect

Classification Estruscycle (days)

Estrus period(days)

OverallmeanYear

1993

19941 995

MontlxJanuaryFebruaryMarchAprilMayJune

14.98+1.12(119) 6.04+0.2q222)

r7.r0*1.44 (40) 6.2Eri}.41 (62)13..82 *t.44 (41) 6.33 *0.40 i63i14.01 +1.62 (38) 5.51 +9.361971

8.01 +5.33 "a13.89 +2.73 t"

15.04 +1.43 t"

15.50 +1.41 I18.84 +1 .39 "18.60 +1.59 "b "

7.22 *0.99 ^

6.11*j0.62b6.28 +0.41 "b

6.62 *9.47 *4.70 +0.45 "5.29*0.50 t"

Figures in parentheses represetrt number of olrr*utio* frg_

fll]!]gg: otre same superscript tetter witnn an effect did notdiffer significantly.

June 1)991

spiit estrus) during early and iate breeding season in thor-oughbred mares.

The overall mean coverings required per lbal born (in-cluding abortions) was 9.87 (76 tbals iiom 760 coverings to140 mares). For thoroughbred horses Badi er a/. (1981) hadreported that out of total services 32o/otvere inf-ertile. in26%embryonic loss occurs and only 40Vo mares lba1 normal1y.

Foaling: Year and month-wise lbaling data analysis overthe penod showed that out of total 64 fbalings, maximurnfoalings occurred in April (19) and March (18) lbilou,ed byFebruary (14), May (11) and.Iune (2). Highest (61.61%)fbalings occurred at night to mid-night, 21.53oA at earlymoming, and only 6.15% of the mares lbaled during dayhours. Only 56.92% ofthe tbaling mares evidenced foal heatwith a mean interval of 7.78+A.72 days liom fbating, iurd amean 2.56 coverings were given per fbal heat. Nishikarva(1959) and Daels et al. (1991) have reported similar lind-ings. The abortion at the stud was 13.15% (10 out of 76)abortions occurring between 4 and 10 months of gestation,40% (4 out of l0) of the aborting mare carried twin tbetuses.Robefts ( I 987) have reported similar findings. The sex ratio(male birth) wx 43.07%,.

Reproduc tiv e dis orders : Reproductive disorders rvererare, the percentages of placental retention, vaginitis,pnuemovagin4 anestru.s during the period were 4.61 , t\.71 ,4.28 and3 .57 o/o, respectively. Repeat breeding rvas only seenduring early or late breeding season when the cyclicity wasabnormal. There was no ca-se of dystocr4 prolapse, nym-phomania or abnormality in the mares. The iow incidence

REPRODUCTI\,E PERFORMA#.E IN MARES 399

of reproductive disorders could be because the thorough-bred horse being valuable is the most cared species and hencereproductive abnormalities are seldom t-ound (Gordon I99T).For reproductive management hCG, LH and PGF"cr werethe most commoniy used drugs at the stud.

ACKNOWLEDGEMENTS

The grace observed by the owners and the manager,Ram Deo Vishwa Nath Stud Farm, Kola^sar (Bikaner), isgratetully acknowledged.

REFERENCES

Badi A MO, Byrne TMandCunningham EP. 1981. An analysisof reproductive performance in thoroughb,red m arcs. Iish Vet-erinan, Joutnal 35 : 1-12.

Daels P F, Hughes J P and Stabenfeldt G H. i 991. Reproduction inhorses. Reprodrrction in Do:mestic Anitnals. 4th edn, pp 413-44.Academic Press, New York.

Ginther O J. 1974. Occurrence of anestrus. estrus. diestrus andor",rlation over a 12-month period in mares. American Jour-nal o.f Veterinary Research 35 z ll73 .

Gordon l. 1997. Controlled Reproduction in Horses, Deer andC am e I i d s . CAB International, Wallingford, LIK.

Nishikawa Y. 1 959. Studies on reproduction in horses. Japan Rac-ing Association, Bulletin. p. 73, Tokyo.

Roberls S J. 1987. Abortion and gestatiinal diseaseirn mares.Curent Therapy in Therioge.nolog. g. 705.(Ed.) MorrowD A. W.B. Saunders Co., Philadelphia, USA.

Snedecor G W and Cochran W G. 1 967. Statistieal Methods. 6lhedn. Oxford and IBH Publishing Co., New Delhi.